Verapamil HCl belongs to the class of drugs called calcium channel blockers. It is used mainly to treat hypertension, angina and some cardiac arrhythmias, but may also be used for migraine prophylaxis. The drug is known by different trade names depending on the country and manufacturer and is available in various forms, including oral formulations, extended-release formulations and injectables. In most countries, verapamil HCl is available only by prescription.
Calcium channel blockers, including verapamil HCl, work by blocking the movement of calcium. Calcium is one of the major players in the contraction of both cardiac muscle and blood vessels. By blocking the flow of calcium, the drugs reduce contraction of the heart and of the blood vessels, thus treating angina and lowering blood pressure. Angina is associated with chest pain that is due to a lack of oxygen in the heart as a result of cardiac or heart spasm.
One of the causes of migraine is vasoconstriction of the blood vessels in the brain. Verapamil HCl has been used prophylactically to prevent migraines, as it may act via the same mechanism. By blocking the flow of calcium, the blood vessels in the brain are dilated and allow free flow of blood, preventing migraines.
As with any medication, verapamil HCl may interact with other drugs, causing them to work less effectively, raising their levels to toxic levels or causing additive adverse reactions. For this reason, any concomitant medication, including supplements and complementary medicines, should be discussed with the prescribing doctor.
The use of verapamil HCl is not advised in patients with some other conditions, such as heart block. The prescribing doctor should be informed of any underlying conditions. Pregnancy, desired pregnancy and lactation should also be discussed before starting treatment.
The drug may cause side effects in some patients. Constipation, headache and postural hypotension, or low blood pressure on standing up causing dizziness, may occur. These side effects may be worse on initiation of therapy and improve over time. Any untoward effects should be reported to the prescribing doctor immediately.
The dose of verapamil HCL will depend on the condition being treated and the formulation used. Dosing may begin with three times daily dosing and go down to twice a day or, if the extended-release preparation is used, once daily dosing. Hypertension and angina are usually chronic conditions, so the drug is used long-term. The prescribed dosage should never be exceeded.